Disinfection of Seeds of Cucurbit Crops Infested with <i>Acidovorax citrulli</i> with Dry Heat Treatment

Abstract

Abstract The Japanese government legally restricts entry of the bacterial fruit blotch disease of cucurbits caused by Acidovorax citrulli . However, the disease has occurred several times in Japan caused by infestations of melon, watermelon and wax gourd seeds with the pathogen. We prepared seeds infested with this pathogen for melon, cucumber, squash, wax gourd and bottle gourd and treated the seeds with dry heat for disinfection from the pathogen, varying the temperature and duration. Percentages of seed infested with the pathogen were determined after the dry heat treatments. The healthy or infested seeds (after the dry heat treatments) were sown in soil and the germination percentage evaluated. Complete disinfection of seeds of melon, cucumber and small‐seeded squash (and without preventing germination) was achieved with some dry heat treatments, with 85°C for 3–5 day being preferable. The large‐seeded squash, wax gourd and bottle gourd were sensitive to dry heat, additionally harsh conditions of ≥90°C and 7 day at 85°C were needed for complete disinfection. Thus, there were no feasible conditions for seed disinfection without affecting germination for the large‐seeded crops.